Multiple unit pile-up switch



vSept. 1, 1959 A. c. BERNSTEIN 2,902,549

' MULTIPLE UNIT PILE-UP SWITCH Filed Aug. 31. 1956 2 Sheets-Sheet 1 rr 42 l l /3 1' t ii i L I V i l r I I I r q' n INVENTOR ALLEN C. EER/VSTE/N BY @WDM-mw ATTORNEY Sept. l, 1959 A. c. BERNSTEIN 2,902,549

MULTIPLE UNIT PILE-UP SWITCH Filed Aug. 31, 1956 2 Sheets-Sheet 2 INVENTOR ALLAN C. BERNSTE/N ATTORNEY MULTIPLE UNIT PILE-UP SWII CH Allan C. Bernstein, Kings Point, N.Y., assignor to ExecutYone( Inc., New York, N.Y., a corporation of New Application August 31, 1956, Serial No. 607,317

8 Claims. (Cl. 200-1) This invention relates to a multiple unit pile-up switch.

In communication systems, such as inter-com or telephone systems provided with a communication instrument which may be selectively connected to various stations in the system, a multiple switch is generally provided at the instrument for this purpose. These switches are generally maintained open and may be individually closed for the connection of one selected station of the multiple number of choices to the specific instrument containing the switch. An actuation mechanism is generally provided for closing the switches which will release a previously closed switch to its open position as a different switch is actuated to its closed position. The individual switches of the multiple switch unit for connecting the communication instrument to the various lines may conveniently be of the pile-up type.

The pile-up switches consist of a multiple number of leaf-spring arms having contact points at one end portion and are spaced apart by insulating members at the other end portion. The leaf-spring arms with their contacts, which will be referred to herein as leaf-spring contacts, are pressed together in contact in order to close the circuit. The pile-up switches generally have at least 4 leafspring contacts, 2 movable, and 2 fixed. The movable contacts are connected together by a suitable insulating member, such as an insulating plate, so that when one movable contact arm is pressed in contact with its opposed fixed leaf-spring contact, the other movable leaf-spring contact will simultaneously move in contact with its opposed fixed leaf-spring contact.

The circuit between the communication instrument and any particular station is generally considered open or interrupted when the contacts are spaced apart, and closed or connected when the contacts are pressed in contact with each other. In pile-up switches, however, the iiat leaf-spring contacts, and, in particular, the opposed fixed and movable leaf-spring contacts act as the plates of the condenser with the insulating member separating the same acting as the dielectric. This, therefore, often results in a capacitance connection between the communication instrument and the particular station when the contacts are open and results in cross-talk, i.e., -the passage of the communication message across communication circuits normally considered disconnected.

The multiple unit pile-up switches conventionally consisted of independently constructed pile-up switches positioned in side-by-side spaced relationship to form the multiple switching unit. The complete and separate construction of each of the individual pile-up switches and the subsequent assemblying into a unit was relatively expensive and time-consuming.

One object of this invention is to overcome the abovementioned disadvantages, provide a pile-up switch, which minimizes the danger of capacitance connection when the switch is in its open position, and which may be very simply and economically constructed as a multiple unit pile-up switch.

lknitted States Patent O lice This, and still further objects, will become apparent from the following description, read in conjunction with the drawing, in which:

Fig. 1 is a perspective view of a portion of a multiple unit pile-up switch in accordance with the invention, showing several switching units;

Fig. 2 is an exploded perspective View of a unit segment of the switch of Fig. 1;

Fig. 3 is a side-elevation of a unit of the switch of Fig. l in the normally open position; and

Fig. 4 is a side elevation corresponding to Fig. 3 and showing the switch in a closed position.

Referring to the embodiment shown in the drawing, the switch has two substantially parallel-positioned, conductive plates 1 and 4. These plates extend the entire length of the multiple unit switch and constitute bus bars. These plates may be made of any desired conductive material, as, for example, thin copper. A thin insulating plate 5, corresponding in shape and somewhat larger in size, is positioned against the side of the conductive plate 1 facing the conductive plate 4. A similar insulating plate 8 is positioned against the face of the conductive plate 4 which faces the plate 1. In the same manner, insulating plates 6 and 7 are provided, positioned adjacent the plates 5 and 8 respectively. These insulating plates 5 and 6 and 7 and 8 may be constructed of any suitable insulating material, as, for example, a thin, transparent acetate foil but are preferably formed of thin laminated Bakelite.

Sandwiched between the insulating plates 5 and 6 is a conductive shield plate Q, and sandwiched between the insulating plates 7 and 3 is the conductive shield plate 10. The shield plates 9 and 10 may each correspond exactly to and be constructed of the same material as the plates 1 and 4 and may additionally contain a terminal strip 11 at one end thereof, which may, for example, be bent and fastened to the chassis of the instrument, in connection with which the switch is used, for grounding.

Positioned at spaced intervals along the laminateformed structure formed by the plates 1, 4, 5, 6, 7, 8, 9 and 10 are the elements which make up the individual pile-up switches of the unit. These elements each consist of a flat, substantially rigid, conductive metal strip 12 positioned in contact with the conductive plate 1 and a corresponding strip 13 positioned in contact with the insulating plate 7. Positioned in contact with the strip 12 and thus in conductive contact with the plate 1 is a flat, leaf-spring contact 14. The contact 14 has a terminal connection 15 at its base end and a contact point in the form of a contact bar 16 which extends transverse to its axis at its free end. A corresponding flat, leaf-spring contact 17 with a terminal connection 18 and a contact point 19 is positioned against the strip 13.

Positioned in contact with the insulating plate 6 is the at, leaf-spring Contact 20, which has the terminal connection 2.1 and the contact point 22, which extends substantially co-axial with its axis. A small rectangular aperture 23 is defined through the upper `free end of the leaf-spring contact 2G.

A leaf-spring 24 is positioned in contact with the conductive plate 4 on the side thereof opposite the insulating plate 8. The leaf-spring contact 24 corresponds to the contact 20, having the terminal connection 25 and contact point 26. In place of the rectangular aperture 23, however, the upper free end of the leaf-spring contact 24 has a rounded V-bend at 27.

The leaf-spring contacts may be constructed of any conductive material having resilient spring-like properties, and are preferably constructed of a conductive spring metal such as nickel-silver.

Positioned in contact with the leaf-spring contact 14 of each pile-up switch unit on the side opposite the conductive plate 1 Ais an insulating spacer 28 and a corresponding spacer 29 is positioned in contact with the side of the leaf-spring contact 17 opposite the insulating plate 7.

An .insulating spacer 30 .is Apositioned =in contact 1`with the contact `springZt) on the sideoppositeftheinsulating plate 6 and a corresponding spacer 'Slisepositioned .in contactk withlthelleaf-spring contact `24 onfthe side'thereof opposite `the conductiveplate 4. The insulating spacers 28, 29, 30 and 31 may be constructed-ofany lsuitable insulatingmaterialand may, for example, be constructed of laminated Bakelite of greater thickness than-the other lates. p With the switch assembled-as Aa :laminate unit, the insulating spacers 30 .Contact kcorresponding 4insulating spacers 29 keeping lthe'leaf-spring contacts 2t) and Vll7 spaced apart and insulated fromeachyother.

Each of the elements ofthe units has'the holes 2 and 3 drilled or punched therethrough with theholes in the plates 1 and 4 through `itl located-at the portions where the individual pile-up switches are tobe positioned. The entire unit is assembled by pressing the insulating sleeves 34 and 35, respectively/through the holes 2 and 3. The frictional contact between insulating sleeves and the walls of the holes, particularly at the insulating spacers hold the unit together. The unit may be assembled on the particular chassis in connection with which it is to be used by merely inserting screws through centers of the sleeves 34 and 35 and screwing the same to the chassis. The screws are completely insulated from the contacts and other conductive elements of the switch by the sleeves and by the insulation spacers. The sleeves 34 and 35 may be constructed of any suitable insulating material as, for example, Bakelite-impregnated ber.

The free end of each of .the leaf-spring contacts .24. is connected to the free end of the opposed aligned leafspring contact Ztl for'benrlingmotion therewith by means of the insulating strip 36. The strip 36 tits into the V- bend 27 of the leaf-spring contact 24 and has a slit 37 with a projection 3S. The slit 37 tits over the leaf-spring contact with the projection 38 extending through the aperture .23. The insulating strip 36 is made of any suitable insulating material, as, forxexample, linen base laminated Bakelite.

Due to the fact that the individual pile-up switches of the unit have common elements, such .as the conductive and insulating plates which additionally serve to maintain the individual switches together as a unit, the production of the multiple-switch unit is greatly facilitated and the cost substantially reduced. The entire unit may be produced `in a single operation by laying the elements one o-n top of the other in their proper sequence on a suitable form or mandrel and thereafter pressing the insulating sleeves in placeto hold the unit together. This readily lends itself to Vautomatic and semi-automatic production. Thus, for example,xall of theinsulating sleeves may be simultaneously pressed in place by a very simple and relatively inexpensive device.

In contrast to this, the individual switches of the conventional multiple-switch unit had to be individually assembled and then the entire unit had to be assembled together on a suitable support plate or on the chassis of the instrument in connection with which the device was to be used.

As mentioned, after the unit in accordance with .the invention is assembled, the same may be very readily connected to the chassis in connection with which the same is to 'be used, by merely screwing the same in place by screws which extendthrough the hollow insulating sleeve. These screws `further serve the purpose of more rigidly holding the unit together and preventing separation of the component parts which might otherwise occur, since the insulating sleeves merely hold the unit together by frictional contact. It is, of course, possible to more securely and permanently anchor the sleeves in place or use other securing devices in addition to or in place of-the sleeve. Thus, for example, a conventional nut and bolt may be inserted through the hollow interior of the sleeve or the sleeve may be replaced by a suitable securing member of insulating material.

In operation the switch may be connected with each of the leaf-spring contacts 14'aud24 connected in parallel to the particular communication instrument in .connection with which the u nit'is used and with each of the contacts 20 and 1-7 connected to adifferent station in the communication system as diagrammatically shown in Fig. 3. The conductive shield plates 9 and 10, respectively, are grounded, as, for example, by connecting the terminal strips 11 to the chassis of the communication instrument or to any other source of ground. This connection may be conveniently made by bending these strips around over the end insulation spacers 28 and by grounding the same by means of the screws which extend through the spacers and insulating sleeves 34 and/or 35'to'the chassis. Thus, for example, a-metal strip may be placed over the insulating spacers 28 secured bythe screws passing through the sleeves *34 and 35 andthe terminal strips 11 may be 'secured beneath 'this'metal strip.

With any indivi'dualpile-up switch open as shown in Fig. l3, a capacitance connection through this switch to the particular station whiclrthe switch connects to is substantially prevented by `means of the grounded shield plates 9'and1t).

In orderto close the switch and thus connect the intercom instrument tothe particular station which passes through the'individual switch, the leaf-spring contact 24 is bent to the-right sothatthe contact 26 and the contact 19 close. Due to the cross-positioning of the bar-shaped contacts, an exact alignmentof the same is not necessary. At the same time, the insulation strip 36 bends the leafspring contact 20,'so'that'the vcontacts 22 and 16 close.

The'metal strips 1:2 and 13 serve to prevent leaf-spring contacts 17'and 14from'moving towardthe left as shown in Figs. 3 and 4, and Vthus laccidentally closing the circuit when the'same'is 'normally open'and to allow these contacts to-be lpre-tensioned in a direction toward the contacts Ztl and 24 respectively. The leaf-spring contacts 14 and 17, howevenwill bend to the right and `do so when the contacts 26and 19, 22 and 16 close, so that the motion of theleaf-spring contacts 20 and 24 need not be exactly controlled and the contact pressure will he substantially uniform once the contacts are closed irrespective of whether the leaf-spring contacts l20 and 24 are bent to the right a greater or lesser amount.

The actuation ofthe leaf-spring contact 24 may conveniently be effected Yby means of a cam 37 of suitable insulating material which isa'ctuated by means of the push button 33 and whichslides on the inclined portion of the V-bend 27. The cams `37 rand buttons 38 for each individual pile-up switch maybe so arranged that when one of the buttons 38 is depressed, any previously depressed button is released to they position as shown in Fig. 3.

While in the particular pile-up switch shown the contacts are normally open and the actuation by means of cam 37 causes .closing thereof, the constructionmay, of course, be reversed, sothat the contacts are normally closed and actuation causes opening thereof. For this purpose, for example, the contacts 20 and 24 may be reversed with the V-bend 27 facing in the opposite directionand with-the springs vbiased so that the contacts are normallyclosed as shown inlFig. 4. Action of the cam 37 ,on the inclined surface of the V-bend 27 will then force the leaf-springs 20 and :24 to the left, lopening the contacts.

While the invention-thas been described in detail with reference to the specific .embodiment shown, various changes and modifications which fall within the'spirit ofthe invention and scopefofithe appended claims'will `hecome apparent to the skilled artisan.

I claim:

1. A multiple unit pile-up switch comprising a iirst conductive plate, a second conductive plate, a rst pair of insulating plates having a first conductive shield plate sandwiched therebetween and a second pair of insulating plates having a second conductive shield plate sandwiched therebetween positioned in a laminate arrangement with said pairs of insulating plates positioned between said conductive plates and with insulating spacer means positioned between said pairs of insulating plates, a multiple number of first substantially fiat leaf-spring contacts positioned in spaced-apart relationship along said first conductive plate in conductive contact therewith, a multiple number of second substantially flat leaf-spring contacts positioned in spaced relationship along the side of the insulating plate of said lirst pair facing said second pair in opposed spaced relationship to said first leafspring contacts, a multiple number of third substantially flat leaf-spring contacts positioned in spaced-apart relationship along the side of the insulating plate of said second pair facing said first pair in opposed spaced alignment with said rst and second leaf-spring contacts, a multiple number of fourth substantially flat leaf-spring contacts positioned in spaced apart relationship along said second conductive plate in conductive contact therewith and opposed spaced relationship to said third leaf-spring contacts, and insulating members connecting the free end portions of said first leaf-spring contacts with the free end portions of said aligned third leaf-spring contacts for bending motion together, whereby each of said lirst leaf-spring contacts may be resiliently pressed in contact actuation with an opposed second leaf-spring contact simultaneously pressing an aligned third leaf-spring contact in contact actuation with an opposed fourth leaf-spring Contact.

2. Multiple unit pile-up switch according to claim 1, including a multiple number of mating holes defined through said conductive plates, said shield plates, said insulating plates, and said leaf-spring contacts, and insulating sleeves pressed through said holes maintaining the unit together at least one hole having an insulating sleeve therein extending through each of said leaf spring contacts.

3. Multiple unit pile-up switch according to claim 2, in which at least a portion of said leaf-spring contacts each has a terminal connection extending past said plates on the end portion thereof adjacent said plate and a contact point at the free end portion thereof, said contact points on opposed contacts being positioned for mating actuation when said rst leaf-spring contact is pressed in contact actuation with said second leaf-spring contact, said contact points being bar shaped contact points extending at substantially right angles to each other on opposed mating leaf-spring contacts.

4. Multiple unit pile-up switch according to claim 3, including a shorter stili strip positioned between each of said second and fourth leaf-spring contacts and their adjacent plates.

5. Multiple unit pile-up switch according to claim 4, in which the free end of each of said first leaf-spring contacts is V-bent with its apex facing in a direction away from said aligned third leaf-spring contact, and in which said insulating members connecting said first and third leaf-spring contacts comprise insulating strips connected to said third leaf-spring contacts and extending into said V-bends.

6. Multiple unit pile-up switch according lto claim 5, in which each of said insulating strips defines a slit with a projection therethrough and in which said third leafspring contacts are positioned extending through said slits and dening aperture with said projections extending therein.

7. Multiple unit pile-up switch according to claim 1, including a shorter stii strip positioned between each of said second and fourth leaf-spring contacts and their adjacent plates.

8. Multiple unit pile-up switch according to claim 1, in which the free end of each of said rst leaf-spring contacts is V-bent with its apex facing in a direction away from said aligned third leaf-spring contact, and in which said insulating members connecting said rst and third leaf-spring contacts comprise insulating strips connected to said third leaf-spring contacts and extending into said V-bends.

References Cited in the iile of this patent UNITED STATES PATENTS 1,199,843 Washburn Oct. 3, 1916 1,784,898 Gary et al Dec. 16, 1930 1,792,496 Hinshaw Feb. 17, 1931 2,154,338 Knos Apr. 11, 1939 2,414,307 Johnson Jan. 14, 1947 2,740,870 Melori et al. Apr. 3, 1956 

